Conventionally, in a heavy load tire such as an off the road radial (ORR) tire and a truck and bus radial (TBR) tire, rubber of a tire side portion(s), especially its portion on a side of a bead portion(s), tends to be deformed due to frictions with a rim flange(s) and thrusts from the rim flange(s). In order to restrict the deformations, taken is a means for increasing a thickness of rubber of the tire side portion, especially its portion on the side of the bead portion. However, heats tend to be generated due to the deformations of the rubber when the thickness of the rubber is increased. The heat generations at the tire side portion promote deteriorations of the rubber and will deteriorate not only endurance of the bead portion but also endurance of the tire, so that desired is a tire in which temperature rises at a portion on a bead portion in a tire side portion can be restricted.
For example, proposed is a means for forming a circumferential depressed portion that is depressed inward from an outer surface of a tire side portion along a tire width direction and is extended along a tire circumferential direction with in a predetermined range of the tire side portion (e.g. Patent Literature 1), and, in a prior-art, temperature rises of a portion on a side of a bead portion in a tire side portion are restricted by such a means.